The street fights we are speaking of, are street fights where your opponent want to beat you mostly bare handed - this is still very classical and happens frequently - instance: http://www.youtube.com/watch?v=uYhYVAm-x4Y
How long would you survive aginst a cop like that, Sir?
I know perfectly how much I would - but you? Are you expert enough to know it beforehand? In fact, experience can reveal to you these things.

I don't know about the other guy, but I'd last nigh on forever. He's flailing all over the place, most of it's upper body movement; it's a mess. Even when the black guy was wide open the white guy couldn't land a telling hit on him.

Dealing with that sort of person's largely a matter of getting your guard up and driving right through the middle of it till you're in a position to take him down. Black guy's problem was he was trying to stand there and box with him - and they were both really bad boxers. The cop was, admittedly, better, but he wasn't much better.